Photoacoustic-based SO₂ estimation through excised bovine prostate tissue with interstitial light delivery

Photoacoustic (PA) imaging is capable of probing blood oxygen saturation (SO₂), which has been shown to correlate with tissue hypoxia, a promising cancer biomarker. However, wavelength-dependent local fluence changes can compromise SO₂ estimation accuracy in tissue. This work investigates using PA imaging with interstitial irradiation and local fluence correction to assess precision and accuracy of SO₂ estimation of blood samples through ex vivo bovine prostate tissue ranging from 14% to 100% SO₂. Study results for bovine blood samples at distances up to 20 mm from the irradiation source show that local fluence correction improved average SO₂ estimation error from 16.8% to 3.2% and maintained an average precision of 2.3% when compared to matched CO-oximeter SO₂ measurements. This work demonstrates the potential for future clinical translation of using fluence-corrected and interstitially driven PA imaging to accurately and precisely assess SO₂ at depth in tissue with high resolution.